1. Technical Field
The present invention relates to an alarm processing circuit and an alarm processing method, and more specifically, to an alarm processing circuit and an alarm processing method in a communication device.
2. Background Art
A communication device typically includes an alarm processing circuit. The alarm processing circuit judges presence or absence of a fault based on a signal (hereinafter referred to as main signal) input to the communication device to perform processing of outputting an alarm signal. More specifically, the alarm processing circuit generates an alarm signal upon judgment that the fault has occurred. However, the processing efficiency may be degraded if the alarm processing circuit outputs the alarm signal every time the judgment is made that the fault has occurred. Accordingly, it is required to perform mask processing on a specific alarm signal in the alarm processing based on setting information of the communication device.
Further, the alarm processing circuit in the communication device generates alarm signals that have a relation with the communication structure or the hardware structure of the communication device. The mask processing needs to be executed on an alarm signal (hereinafter referred to as secondary alarm signal) other than the alarm signal that warns of the cause of the fault (hereinafter referred to as cause alarm signal) among these alarm signals. More specifically, the alarm processing circuit performs the mask processing on the secondary alarm signal based on the cause alarm signal. Thus, the alarm processing circuit is able to output only the cause alarm signal.
In general, a dozen to several dozens of alarm signals are defined for each communication line as the alarm signals that are generated based on the main signal. These alarm signals are divided into the cause alarm signal and the secondary alarm signal.
A transmission device disclosed in Japanese Unexamined Patent Application Publication No. 08-070290 stores state information indicating a state of each path or each line in the transmission device. Further, state information that is input (present state information) is compared with state information that is stored (previous state information). When the previous state information and the present state information are different from each other, it is judged that the state of each path or line in the transmission device has changed. Then, the fault that causes this change is detected and stored. Further, a secondary mask pattern is generated based on the fault. Then, the mask processing is performed on the secondary alarm signal using the secondary mask pattern.
However, according to the above-described alarm processing, the secondary alarm signal is subjected to the mask processing based on the cause alarm signal, and thus, the mask processing performed on one alarm signal gives an influence on the generation condition of other alarm signals. It is thus difficult to perform maintenance such as design specification.
Further, the processing time to perform the mask processing on the secondary alarm signal based on the cause alarm signal exponentially increases with respect to the number of alarm signals. For example, if the number of alarm signals is doubled, the mask processing of up to four times (2×2 times) is required. Further, the number of alarm signals that is generated is also increased in accordance with the increased number of signals that are treated in the communication device. As such, the mask processing in the alarm processing is one of the factors to inhibit the high performance of the communication device.
In the transmission device disclosed in Japanese Unexamined Patent Application Publication No. 08-070290, when there is no difference between the previous state information and the present state information, further processing is stopped to shorten the processing time. However, according to the transmission device disclosed in Japanese Unexamined Patent Application Publication No. 08-070290, some systems are required such as a comparator that compares the previous state information with the present state information and software that realizes the comparing. Further, as it takes time to perform the comparison, the processing time of the whole alarm processing can hardly be shortened.
Furthermore, in the communication device, the alarm processing is often realized by software. Accordingly, the processing result of the alarm processing depends on the order of the alarm processing. More specifically, each alarm signal is sequentially generated in the software processing. Thus, the final mask processing result may be different depending on the order of the alarm processing. For example, assume a case in which there are two piles that “mask processing is performed on an alarm signal B based on an alarm signal A” and “mask processing is performed on an alarm signal C based on the alarm signal B”. In such a case, as the alarm signal B has already been subjected to the mask processing when the first rule is performed first, the second rule is not performed. Thus, the alarm signal C is not subjected to the mask processing. On the other hand, when the second rule is performed first, the alarm signal C is subjected to the mask processing first. Then, the first rule is executed, and thus the alarm signal B is also subjected to the mask processing. As such, the final mask processing result is different depending on at which time and which alarm signal is subjected to the mask processing. Accordingly, it is difficult to make clear the range that is influenced by the change in changing the mask relation in the maintenance of the design specification or the like.
This problem can be avoided by creating special mask processing for each alarm signal. However, the increase of the number of alarm signals leads to the increase of the number of the special mask processing. Thus, the mask processing in the alarm processing degrades the performance of the communication device.
Further, it should be considered at which timing of the alarm processing and how the mask processing should be performed, or to what extent the alarm signal that is used for the mask processing is processed. Thus, the relation between the alarm signals becomes complicated. Thus, if the number of alarm signals increases, the maintenance of the change to the specification or the like becomes significantly difficult compared with the increased amount of the alarm signals.